1. Field of the Invention
Embodiments of the present invention generally relate to display screens, and more specifically, to systems and methods for calibrating multiple light sources of such display screens to produce a more uniform image.
2. Description of the Related Art
Electronic display systems are commonly used to display information from computers and other sources. Typical display systems range in size from small displays used in mobile devices to very large displays, such as tiled displays, that are used to display images to thousands of viewers at one time. Multiple light sources are commonly used in such displays. For example, in laser-phosphor displays (LPDs), multiple lasers may be used to simultaneously “paint” different regions of phosphor-containing regions to produce an image for a viewer, where the optical output energy of each laser paints a different phosphor-containing region of the display. Similarly, displays using organic light-emitting diodes (OLEDs) may include multiple light sources, such as banks of light-emitting diodes (LEDs), each light source providing illumination for a specific region of the display screen.
Because the human eye can readily perceive small differences in brightness uniformity of a displayed image, the use of multiple light sources in a display system can produce visual artifacts in an image when the output of each light source is not tightly controlled. Differences in brightness as small as 1% between adjacent light sources are apparent to a viewer, so each light source of a display system must be calibrated to generate light energy with a variation of less than 1% from the other light sources. Otherwise, display system brightness will appear non-uniform. For example, in LPDs, in which each laser may illuminate a different row of pixels on a display screen, lines of higher or lower brightness may be apparent to the viewer if the mismatch in laser power is greater than approximately 1%. Although difficult, providing a display system with multiple light sources having such low mismatch in power output is needed because of manufacturing variations between each light source as well as drift in the performance of each light source over time.